Field of Invention
The current invention concerns a method for multiple layer alginate coating of biological tissue, cells and cell lines. In particular, the invention concerns cells or tissue coated with multiple layers of purified alginate. The method includes applying a first coat of soluble alginate gelled with divalent cations, optionally followed by treatment with other divalent cations, removing excess cations, resuspending the single coated cells or tissue in soluble alginate to form an intermediate halo layer around the first coating via exchange or diffusion of divalent cations from the single coating to the surrounding soluble alginate, dispersing the excess soluble alginate, and gelling the remaining thin layer of soluble alginate by contact with divalent cations to form an outer layer coating. Thus, a multi-layer structure is formed wherein biological tissue or cell core is covered with a first coat layer, which is optionally surrounded by an intermediate halo layer, which is in turn covered by an outer coating layer.